??????????????????????`dispatch_async`???????????κ?UIKit?????????????????????С?

?????????? NSOperation ????GCD ??????????????????Ray Wenderlich?? Multithreading and Grand Central Dispatch on iOS for Beginners?? ???? Soheil Azarpour ?? How To Use NSOperations and NSOperationQueues ????

????6. ??Image Views?е???????С

??????????`UIImageView`????????????bundle?????????????????С??UIImageView???С???????????????????????????????????`UIImageView`?????`UIScrollView`?е???????

?????????????????????????????????С????????????????????????С??????????????????????????background thread????????Σ??????UIImageView???????????????

????7. ????????Collection

???????????????????????????????д????Ч??????????????????collections???仰?????????

????Apple????? Collections Programming Topics ?????????????????classes?????????????Щ????????????????????κ????collections??????????????????????

????????????????????????…?????Щ????collection?????

????Arrays: ??????????????index??lookup??????value lookup?????? ????/?????????

????Dictionaries: ?洢?????? ?ü??????????

????Sets: ??????????????????????????/??????

????8. ??gzip???

????????app???????????????????API?????????????????????????XML?? JSON?? HTML?????????????app??

????????????????????????豸????????????????????ж?á??????????????edge???磬???????????л?????3G??????????????????????????????????????

??????С???????????????????????app?д?gzip??????????????????и???????????????????и???????Ч?á?

????????????iOS?????NSURLConnection??????????gzip????????AFNetworking??Щ?????????????????Google App Engine??Щ??????????????????????????

???????????????????Apache????IIS(??????)????gzip?????????????????

?????м?????????

?????????????????????????Щ???????????????????????????????????Щ???????????????Щ??????????????????????????????μ??????д???app?????????Щ???????????Щ???????

????9. ???ú???????(lazy load) Views

?????????view??ζ??????????????????CPU?????????????????????????view??UIScrollView????app????????

?????????????????????????`UITableView`??`UICollectionView`?????: ?????δ??????е?subview????????????????????????????????????????????????????????С?

??????????????????????????????????views????????????????????

????????views????Ч?????????????app?????????檔?????????????????????????????????????view?????????????????????

????1. ?????????????view?????screen???????????????????;

????2. ?????????????????

??????????????????????

???????????????????????????????????view???????????????????????????????檔????????????app???????????????????????????????????????????view???????

????????????????-?????????棬??????????????????????????????

????10. Cache?? Cache?? ????Cache!

???????????????????????????????????Щ????????????????????????????

?????????????Щ??????Щ?????????????????????????????????????????UITableView???и??

????NSURLConnection?????????????????洢?и????????????HTTP Headers??????????????????????NSURLRequest??????????????????

?????????????????????Σ??????????????????????????????????????NSURLRequest??????????
 
+ (NSMutableURLRequest *)imageRequestWithURL:(NSURL *)url {
    NSMutableURLRequest *request = [NSMutableURLRequest requestWithURL:url];
 
    request.cachePolicy = NSURLRequestReturnCacheDataElseLoad; // this will make sure the request always returns the cached image
    request.HTTPShouldHandleCookies = NO;
    request.HTTPShouldUsePipelining = YES;
    [request addValue:@"image/*" forHTTPHeaderField:@"Accept"];
 
    return request;
}